I don't have a quilting guru right now, but in the past it was definitely Eleanor Burns and Georgia Bonesteel. Took classes with both. I've also taken quite a few applique classes just because I always learn something new from each instructor. Took classes with Ellie Sienkiewicz and Mary Sorenson, as well as several others. Took a LA class with Linda Taylor on doing feathers even though I'm not a LA'er. I have an upcoming 4-day class with David Taylor, another appliquer.
Right now my interest is in denser FM. But I've had several classes on that, including one with Diane Guadynski. (I've probably misspelled everyone's name!). So it's not likely I'd take another class on that.
Classes are fun. The possible only downsides for me are gathering up a bunch of special supplies that may not be used in class and the distinct possibility of another expensive UFO.
And I've also enjoyed and learned from many local/regional instructors.